LAUSR

Abstract Little research has been carried out monitoring fitness of mules. Therefore, there is a need to define fitness indices for such species that is commonly used for work and athletic purposes under tropical conditions. The objectives were to evaluate the influence of a field marcha test on some blood and electrocardiographic parameters of mules. Ten Pêga mules, 4.7 ± 1.3 year old and 405.7 ± 35.7 kg were used in the study. Heart rate (HR), respiratory rate (RR), body temperature (BT), and blood sampling were obtained before (T0) and immediately after exercise (T1), and at 30 minutes (T2) and 120 minutes (T3) of recovery. Blood analysis included erythrogram, leukogram, serum aspartate aminotransferase (AST), creatine kinase (CK), total protein, triglycerides, plasma lactate, and glucose. Electrocardiographic variables (measurement of P, R, and T wave amplitudes, in mV, and duration, in ms, of P wave, QRS complex, PR and QT intervals, heart rate and rhythm) were analyzed at T0, T1, and T2. All variables were analyzed for normality through Kolmogorov–Smirnov test, and comparisons were made using the Tukey test, considering P ≤ .05. Exercise testing significantly altered physiological and blood parameters, with higher values recorded at T1, except for CK, total protein, mean corpuscular volume, mean corpuscular hemoglobin concentration, white blood cell count, and monocytes and eosinophils count. Sinus rhythm occurred in 100.0% of mules at all evaluation periods. Electrocardiogram records showed a significant increase in HR in T1. Other findings included significant reductions in T1 for QRS durations and PR and QT intervals, and significant increase in T2 for P wave amplitude. It was possible to conclude that the marcha gait led to important alterations physically well‐conditioned mules and results differed in several aspects from values recorded for donkeys and equines, reinforcing the importance of obtaining specific values avoiding invalid comparisons between equids. HighlightsBrand new research evaluating electrocardiogram and blood parameters of trained mules.No research studies have been performed with mules used for athletic purposes in Brazil.Comparisons between mules and horses are not valid.Electrocardiographic and blood alterations were observed after exercise.Results can be used on the evaluation of mules trained in tropical conditions.